Ask HN: Profitability of a niche mobile app strategy in 2020?

There are plenty of niche categories--at least marginally popular--that have low quality app options across the board.

I'm new to mobile development, but am wondering if anyone pursues this as a strategy: Identify underserved category where creating a better mousetrap wouldn't be too difficult. Build, submit, repeat in a new niche.

I understand one is at the mercy of the app stores, but if the app is truly best in class I imagine some light promotion + organic store search would be enough to get the flywheel of positive reviews going. To work, the category would need to be small enough that new entrants are like to get a look, but big enough that some money can be made.

Has anyone done this or have a first-hand account of the viability of niche app strategy today? Any insight would be appreciated.